The present invention relates to bearing sleeves used in foil air bearing assemblies for turbomachinery shafts, such as for use with turbochargers or fuel cell turbocompressors.
Air compressors are employed in conjunction with internal combustion engine systems and fuel cells for various purposes. For example, an exhaust gas-driven turbocharger is used in conjunction with an internal combustion engine for increasing the power output by compressing charge air delivered to the air intake of the engine to be mixed with fuel and burned in the engine. By providing compressed air to the intake manifold of the engine, the engine is able to produce more power and to work more efficiently. In conventional turbochargers, exhaust gas enters a turbine side of the turbocharger and serves to spin the turbine, which is mounted to one end of a shaft. A compressor wheel is mounted to the other end of the shaft. Rotation of the turbine rotates the compressor wheel and compresses the air for delivery to the engine intake.
Similarly, a compressor, such as a dual-stage or series compressor, can be used to increase the efficiency of a fuel cell by providing compressed air to the cathode side of the fuel cell. In a dual-stage compressor, a low pressure compressor wheel is provided at one end of a shaft, and a high pressure compressor wheel is provided at the other end of the shaft. Air entering the low pressure side of the dual-stage compressor is compressed, and the compressed air is passed on to the high pressure side for a further increase in pressure.
In either case, a shaft connects the two rotating elements (the turbine and the compressor wheel or the low pressure compressor wheel and the high pressure compressor wheel). This rotating shaft is typically supported by one or more bearings.